Is Claude Opus 4.8 (Fast) available on FastMetal?

Not at the moment. Claude Opus 5.5, from the same lab, is available on the FastMetal API today.

What is the context window of Claude Opus 4.8 (Fast)?

1,000,000 tokens, shared between the prompt and the response.

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Anthropic

anthropic/claude-opus-4-8-fast

Not Available

Claude Opus 4.8 (Fast)

Fast-mode variant of [Opus 4.8](/anthropic/claude-opus-4.8) - identical capabilities with higher output speed at 2x pricing relative to regular Opus 4.8. Learn more in Anthropic's docs: https://platform.claude.com/docs/en/build-with-claude/fast-mode

5/27/2026

1,000,000 tokens

Specifications

Modalities

Input

text

image

file

Output

text

Supported Parameters

include_reasoning

max_tokens

reasoning

reasoning_effort

response_format

stop

structured_outputs

tool_choice

tools

verbosity

Max Output Tokens

128,000

Data policy

Prompt retention: Unknown — we could not confirm
Training: Unknown — not declared

"Unknown" does not mean "safe". It means we could not confirm it.

Whether a provider trains on prompts is a declared value from our terms with them. Retention is determined from the upstream listing for every host this model can reach. Neither is guessed.

Frequently asked questions

Is Claude Opus 4.8 (Fast) available on FastMetal?: Not at the moment. Claude Opus 5.5, from the same lab, is available on the FastMetal API today.
What is the context window of Claude Opus 4.8 (Fast)?: 1,000,000 tokens, shared between the prompt and the response.

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